GREEN-HOUSE STRUCTURES. Ill 



a complete draft, so that the heated air from the furnace 

 is so rapidly carried through the entire length of the flue, 

 that it is nearly as hot when it enters the chimney as 

 when it left the furnace. This perfect draft also does 

 away with all danger of the escape of gas from the flues 

 into the green-house, which often happens when the 

 draft is not active. Although no system of heating by 

 smoke flues is so satisfactory as by hot water, yet there 

 are hundreds who have neither the means nor the inclina- 

 tion to go to the greater expense of hot-water heating, 

 and to such this revived method is one that will, to a 

 great extent, simplify and cheapen the erection of green- 

 houses. Many old-established florists, who have had the 

 old plan of flues in use, have changed them to the one 

 here described, and with great satisfaction. The wonder 

 is that such an important fact has been so long over- 

 looked, for at the time it was discovered heating green- 

 houses by flues was almost the only method in use. 



Figure 7 (one-eighth of an inch to the foot scale) 

 shows a green-house 20 feet wide by 50 feet long, with 

 furnace room, or shed, 10x20 feet. Here the flues are 

 so disposed as to avoid crossing the walks, being placed 

 under the center bench, but as near as possible to the 

 walk on each side, so that the heat may be evenly dif- 

 fused throughout. If a difference in temperature is re- 

 quired in a house of this kind, it may be obtained by 

 running a glass partition across the house, say at 25 feet 

 from the furnace end, which will, of course, make the latter 

 end the hottest. It will be observed that the plan (Figure 

 7) shows by dotted lines this new or revived plan of flue 

 heating. Figure 8 (the same scale) is a section, showing 

 the arrangement of the benches, etc. 



In constructing the furnace for flue heating, the size 

 of the furnace doors should be, for a green-house 20 x 50, 



